This invention relates to a method of stabilizing aqueous organosilane/fluoroorganosilane solutions containing silicon bonded hydrolysable groups.
Aqueous organo/fluoroorganosilanes solutions containing silicon bonded hydrolysable groups have several uses. The hydrolysable groups enable such compounds to irreversibly attach themselves to substrates containing hydroxyl or other silicone reactive species.
The significance of this xe2x80x98tetheringxe2x80x99 action, in this instance, is to retard re-soiling, impart shine and make easier to clean a variety of bathroom surfaces such as enamel, plastic and porcelain, also giving residual antimicrobial/algicidal activity.
It is desirable that the xe2x80x98tetheringxe2x80x99 agent is delivered via a predominately aqueous media with minimal solvent content.
Studies undertaken by the present inventor in order to accomplish the above purpose revealed that the use of one or more non-ionic surface active agents, one of which should be an alkyl saccharide, together with a silane derivative produced an improved detergent composition which helps to prevent re-soiling, gives residual antimicrobial/algicidal properties and residual xe2x80x98Shinexe2x80x99 characteristics. Accordingly, in one embodiment the subject invention provides a solution as defined in claim 1 comprising an alkyl saccharide surface active agent and a silane derivative, and in another embodiment the subject invention is directed to use of said alkyl saccharide in storage stable compositions.
Hard surface cleaning can be achieved with the composition of the subject invention in the absence of water soluble organic quaternary ammonium compounds contrary to the disclosure in a previously published patent U.S. Pat. No. 5,411,585. The composition, instead, stabilizes the organosilane/fluoroorganosilane by the use of saccharides sometimes with an additional non-ionic co-surfactant. For environmental reasons the absence of ammonium quaternary compounds is desired.
Other and further objects, features and advantages of the invention will appear more fully from the following description.
All amounts given herein (in the absence of a statement of the contrary) are given as amounts by weight of the total amount of the aqueous solution of the subject invention.
Organosilanes which can be used in the invention are disclosed in reference U.S. Pat. No. 5,411,585.
The organosilanes having hydrolysable groups which are useful in this invention form clear solutions in water at room temperature (20xc2x0 C.) at least to the extent of the active concentration level to be used in the aqueous solutions. Examples of such organosilanes are methyltrimethoxysilane, 3-(trimethoxysilyl)propyldimethyl-octadecyl ammonium chloride and 3-(trimethoxysilyl)propyl-methyldi(decyl)ammonium chloride. We have found that compounds which do not give clear solutions in water at 20xc2x0 C., such as 3-(triethoxysilyl)propoyldimethyloctadecyl ammonium chloride are not useful in the present invention.
As mentioned above, the aqueous organosilane/fluoroorganosilane solutions of the subject invention are stable solutions. Stable solutions are clear solutions which do not show haze.
Preferably said solutions are storage stable, i.e. said solutions are clear and non-hazy after storage.
More preferably said storage stable solutions are clear and non-hazy after storage at room temperature (20xc2x0 C.) for 6 months, even more preferably after such storage for 1 year.
Preferably said organosilanes have structural formula
A3xe2x88x92xBxSiDxe2x80x83xe2x80x83(1)
wherein each
A is xe2x80x94OH or a hydrolysable group,
B is an alkyl group of from 1 to 4 carbon atoms,
x has a value of 0, 1 or 2, and
D is a hydrocarbon group of from 1 to 4 carbon atoms, a fluoro substituted (otherwise substituted or unsubstituted) hydrocarbon group, phenyl, or a nonionic or cationic, substituted-hydrocarbon group containing at least one oxygen or nitrogen group or salts of such substituted-hydrocarbon groups.
In the above formulas, A is xe2x80x94OH or a hydrolysable group such as a halide like xe2x80x94Cl, xe2x80x94Br and xe2x80x94I, alkoxy or alkoxyether such as those of the formula xe2x80x94OR1 and xe2x80x94OR2AOR1 where each R1 is R2 or hydrogen, R2 is an alkyl group of from 1 to 4 carbon atoms such as methyl, ethyl, propyl, butyl or xe2x80x94CH2CH2CH2(CH3), with methyl being preferred, and R2A is a divalent saturated hydrocarbon group of from 1 to 4 carbon atoms such as methylene, ethylene, propylene, butylene or xe2x80x94CH2CH2CH(CH3)xe2x80x94 with ethylene and propylene being preferred; amino such as xe2x80x94N(R1)2 such as xe2x80x94NHCH3, xe2x80x94N(CH3)2 and xe2x80x94N(CH2CH2)2, also including organosilazanes where two organosilanes are combined by a xe2x80x94NHxe2x80x94 unit; acetoxy which is xe2x80x94OOCCH3; acetamido which is xe2x80x94HNOCCH3; and hydride which is xe2x80x94H, among others known in the art. B is R2 with methyl being preferred.
D is a hydrocarbon group such as R2, vinyl, allyl, phenyl, fluoro substituted (otherwise unsubstituted or substituted) hydrocarbon and nonionic or cationic, substituted-hydrocarbon groups containing at least one oxygen or nitrogen group as well as salts of such substituted-hydrocarbon groups. Examples where D is a fluoro substituted (otherwise unsubstituted or substituted) hydrocarbon group include perfluoroalkylsulphonamide Nxe2x80x94Gxe2x80x94C4 alkylene silanes. Examples of the latter substituted-hydrocarbon groups include 
and xe2x80x94R3Q where Q represents a functional group, optionally with further alkyl or aryl chains, such as alcohols and ethers such as xe2x80x94(OCH2CH2)zOR1 where z has a value of from 0 to about 50, esters or amides such as xe2x80x94COOR6, xe2x80x94CONHR6, xe2x80x94HNOCR6 or xe2x80x94OOCCH(R6)3H1-3CHCH2 where R6 is an alkyl group of 1 to 18 carbon atoms such as methyl, ethyl, butyl, octyl and octadecyl with methyl being preferred and s is 0 or 1, glycidoxy such as xe2x80x94OCH2CHOCH2 as well as other nonionic or cationic substituted-hydrocarbon groups known in the art. In the above formulas, x has a value of 0, 1 or 2 with values of 0 or 1 being preferred, and with x having a value of 0 being most preferred; y has a value of 0, 1 or 2; R3 is a divalent saturated hydrocarbon group of from 1 to 12 carbon atoms such as R2A, xe2x80x94(CH2)6xe2x80x94, xe2x80x94(CH2)8xe2x80x94, and xe2x80x94(CH2)12xe2x80x94; R4 and R5 are each selected from the group consisting of alkyl groups of 1 to 18 carbon atoms, xe2x80x94CH2C6H5, xe2x80x94CH2CH2OH and xe2x80x94CH2OH. R6 is an alkyl group of 1 to 18 carbon atoms. One example of xe2x80x94R3Q is glycidoxypropyl or xe2x80x94(CH2)3OCH2CHOCH2. X is an anion and more preferably, is selected from chloride, bromide, fluoride, iodide, acetate, methosulfate, ethosulfate, phosphate or tosylate anions and most preferably, X is a chloride anion.
In Formula II above, R4 and R5 are preferably alkyl groups of from 1 to 18 carbon atoms and more preferably, R2 is a methyl group with the total number of carbon atoms in R3, R4 and R5 being at least 12 if antimicrobial properties are desired from the organosilane. In one preferred organosilane of Formula II, R3 is a propylene, R2 and R4 are each methyl groups and R5 is an octadecyl group while in another alternative preferred organosilane of Formula II, R2 is a methyl group and R4 and R5 are each decyl groups.
The most preferred compounds for use in the present invention are (CH3O)3SiR2, particularly where R2 is methyl, (CH3O)3SiCHxe2x95x90CH2, (CH3)3SiCH2CHxe2x95x90CH2, (CH3O)3SiCH2CH2CH2OCH2CHOCH2, (CH3O)3SiR2N(R4)yH2xe2x88x92y, (CH3O)3SiR3N(+)(R4)yH3xe2x88x92yX(xe2x88x92), (CH3O)3SiR3NHR3N(R4)yH2xe2x88x92y, (CH3O)3SiR3NHR3N(R4)yH3xe2x88x92yX(xe2x88x92), 
where R3 is propylene and of the nitrogen-functional organosilanes, the most preferred are 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride having the formula
(CH3O)3Si(CH2)3NN(+)(CH3)2C18H37Cl(xe2x88x92)
and 3-(trimethoxysilyl)propylmethyldi(decyl)ammonium chloride which has the formula
xe2x80x83(CH3O)3Si(CH2)3N(+)CH3(C10H21)2Cl(xe2x88x92)
Preferably the organosilane is present in the aqueous solution in an amount of from 0.001% to 5% by weight of the aqueous solution, more preferably from 0.01% to 2% by weight of the aqueous solution and even more preferably from 0.05% to 0.5% of weight of the aqueous solution.
Alkylsaccharides are well known in the art. They are sugar derivatives in which the hydroxyl group attached to carbon 1 is substituted by an alkyl group. Alkylsaccharides describe compounds whatever the constituent sugar whereas alkyl glucosides describe compounds which contain glucose as the sugar.
A typical alkylsaccharide surface active agent which can be used in the present invention is that represented by following formula III
R10xe2x80x94Oxe2x80x94(R12O)txe2x80x94(G)pxe2x80x83xe2x80x83III
wherein R10 is a linear or branched alkyl, alkenyl or alkylphenyl group having 6-18 carbon atoms, R12 is an alkylene group having 2-4 carbon atoms, G is a reduced saccharide residue having 5-6 carbon atoms, t is a value of 0-10, and p is a value of 1xe2x80x9410.
Among alkylsaccharides represented by formula III, those having an alkyl group of C6-18, especially of C8-14, more especially C8-10 for R10 such as octyl, decyl or lauryl are preferable. t in formula III which indicates the condensation degree of alkyleneoxide, is a value of 0-10, preferably 0-4, and most preferably 0. G in formula III, which is the basic unit of the hydrophilic portion of the alkylsaccharide, is a reduced saccharide residue having 5-6 carbon atoms. Glucose, galactose and fructose are preferable reduced saccharide residues. The average polymerization degree of saccharide indicated by p in formula III is 1-10, and preferably 1-4.
Alkylsaccharides are more easily biodegradable than other known stabilizers.
Preferably the alkylsaccharide is present in an amount of from 0.001 to 5 wt. % of the aqueous solution, more preferably 0.1-3 wt. % of the aqueous solution, even more preferably 0.6 to 2.5 wt. % of the aqueous solution.
Optionally said alkyl saccharide can be present in combination with a nonionic surfactant.
Suitable nonionic surfactants can be alkoxylated alcohol nonionic surfactants which can be readily made by condensation processes. A great variety of such alkoxylated alcohols especially ethoxylated and/or propoxylated alcohols are also conveniently commercially available. Surfactants catalogues are available which list a number of surfactants, including nonionics.
Preferred alkoxylated alcohols are nonionic surfactants according to the formula R15O(E)e(P)kH where R15 is a hydrocarbon chain of from 2 to 24 carbon atoms, E is ethylene oxide and P is propylene oxide, and e and k which represent the average degree of respectively ethoxylation and propoxylation, are of from 0 to 24. The hydrophobic moiety of the nonionic compound can be a primary or secondary, straight or branched alcohol having from 8 to 24 carbon atoms are more preferably 7-9 carbon atoms. More preferred nonionic surfactants for use in the compositions according to the invention are the condensation products of ethylene oxide with alcohols having a straight alkyl chain, having from 6 to 22 carbon atoms, wherein the degree of ethoxylation is from 1 to 15, preferably from 5 to 12. Yet more preferred nonionic surfactants for use in the composition according to the subject invention are the condensation products of 4 moles of ethylene oxide with 1 mole of straight-chain C7-C9 alkyl alcohol, i.e. nonionic surfactants according to the above formula where R15 is a straight-chain C7-C9 alkyl group; where p is zero and where e is four.
Preferably the nonionic surfactant is present in an amount of 0.001 to 2 wt. % of the aqueous solution, more preferably in an amount of 0.5 to 1.0 wt. % of the aqueous solution.
The ratio of the alkyl saccharide to the nonionic surfactant is most preferably 1:0.7.
In a particular preferred embodiment of the subject invention a synergistically stabilizing effect is achieved with a combination of the said alkyl saccharide and said nonionic surfactant.
Optionally, from 0.1 to 25% by weight of the total aqueous solution can be water soluble solvents such as butyl carbitol, dipropylene glycol monomethylether, propylene glycol, carbitol, methoxypropanol, glycerine, isopropanol and ethanol. Preferably, methanol is avoided, although the methanol present in commercially available solutions of quaternary ammonium functional organosilanes is well tolerated by the aqueous solutions prepared by the method of the present invention.
Optionally, other ingredients which are compatible with the water soluble organosilanes and surfactants may be included such as from 0.1% to 5% based upon the total weight of aqueous solution of a thickening agent such as hydroxyethyl cellulose, xanthan gum, or conventional thickening agent. Particulate additives such as silica and other high surface area particles are to be avoided since the organosilane may deposit on such particles and thus remove it from the aqueous solutions. Similarly conventional additives such as perfumes, dyes, buffering agents, water soluble metal salts, detergent builders, chelating agents such as EDTA and salts thereof, can be included in the aqueous solutions of the present invention provided that they are compatible with the other ingredients present.
Organo/fluoro-organosilane solutions should preferably be freshly prepared before use in the methods and compositions of the subject invention to prevent loss of activity. The pH of the solutions of the subject invention can be adjusted across a wide range for example from about pH 1 to pH 13-5. However a pH range of 2-10 is preferred and a pH range of 2-5.5 is more preferred.
The pH of the aqueous solution can be adjusted in the appropriate range using an appropriate organic or inorganic acid such as citric acid, acetic acid, hydrochloric acid, phosphoric acid or sorbic acid or an appropriate organic or inorganic base such as sodium hydroxide, ammonium hydroxide dimethyl amine and ethanol amine.
The advantage of the compositions and methods of the present invention is that the aqueous solutions of the water-soluble organosilanes are stable under a much wider range of pH than is presently known in the art. For example, the art teaches that aqueous solutions of alkyl silanes can be brought to a pH of 3.5 to 5.0 using acetic acid, preferably to pH 3.5, but the solutions are said to form insoluble products which render the solutions hazy at which time the solutions should be discarded. Aqueous solutions made according to the present invention have a much longer useful life.